The present invention relates to new pharmaceutical formulations, their preparation and their use in treatment of disease In particular the present invention relates to pharmaceutical formulations of the anti-migraine drug zolmitriptan for nasal application.
Zolmitriptan has the chemical name (S)-4-{{3-[2-(dimethylaminoethyl]-1H-indol-5-yl]methyl]-2-oxazolidinone. Zolmitriptan is a selective 5HT1-receptor agonist. The 5HT1-receptor mediates vasoconstriction and thus modifies blood flow to the carotid vascular bed. 5HT1-receptor agonists are beneficial in the treatment (including prophylaxis) of disease conditions wherein vasoconstriction in the carotid vascular bed is indicated, for example migraine, cluster headache and headache associated with vascular disorders, hereinafter referred to collectively as xe2x80x98migrainexe2x80x99. Zolmitriptan has been developed for the acute treatment of migraine in the form of a 2.5 mg and 5 mg tablet intended to be taken up to a maximum of 15 mg per day.
Although zolmitriptan is a successful drug of considerable benefit to migraine sufferers, there is a continuing need for alternative methods for the direct treatment of migraine and the prophylactic treatment of migraine. In particular, patients suffering from migraine or the onset of migraine need fast relief of their suffering.
Zolmitriptan is a member of a class of drugs known as triptans, for example sumatriptan, naratriptan and rizatriptan, which are prescribed for the treatment of migraine. The leader in terms of sales is sumatriptan which has been marketed as an oral formulation. A subcutaneous formulation was also developed; this was more efficacious (P. Tfelt-Hansen, Cephalalgia 1998, Vol. 18(8), page 532-8) and gave a faster onset of action but was not so acceptable to the patient. An intranasal spray was also developed. This was more user-friendly than the subcutaneous injection but was reported to be less effective in reducing the symptoms of migraine attacks (C Dablof, Cephalalgia 1998; 18(5); 278-282). Also, many patients reported an unpleasant bitter taste after using the nasal spray.
The present inventors sought a formulation of zolmitriptan that achieved fast relief whilst maintaining high efficacy. They also sought a formulation that, for the wide variety of patients that suffer from migraines, had a more acceptable route of administration than a subcutaneous injection. Clearly, the thought of a subcutaneous injection may dissuade many patients from taking appropriate and necessary treatment. Furthermore, the inventors sought a formulation that was convenient, effective and acceptable to the patient and did not cause any unnecessary irritancy or side-effects.
U.S. Pat. No. 5,466,699 discloses a class of chemical compounds for the treatment and prophylaxis of migraine. U.S. Pat. No. 5,466,699 discloses that this class of compounds may be formulated for oral, sublingual, buccal, parenteral (for example subcutaneous, intramuscular or intraveneous), rectal, topical and intranasal administration and examples of such possible formulations, including an example of an intranasal formulation, are disclosed. The intranasal formulation consists of an active ingredient, methyl hydroxybenzoate (0.2%), propyl hydroxybenzoate (0.02%), citrate buffer and sufficient hydrochloric acid to take the pH to 7.
The present inventors devised an intranasal formulation of zolmitriptan that provided effective and improved fast relief for migraine sufferers. Although, the inventors do not wish to be bound by theory, it is thought that this is at least partly due to the direct mucosal absorption of a significant proportion of zolmitriptan administered by the intranasal route.
Furthermore, studies with an intranasal formulation of zolmitriptan having a pH of above 7.0, at a pH of 7.4, showed the stability of that formulation would not be acceptable over extended periods of time.
The present inventors provided an improved rapid onset of action with a stable intranasal formulation of zolmitriptan having a pH of below 7.0. In addition, this formulation was acceptable to the general patient population and did not cause unnecessary irritancy or side effects.
Accordingly the present inventors provide a pharmaceutical formulation suitable for intranasal administration which comprises zolmitriptan and a pharmaceutically acceptable carrier wherein the pH of the formulation is less than 7.0.
The zolmitriptan formulation for intranasal administration is generally prepared as an aqueous formulation and typically is buffered. Suitable buffering agents include citric acid, phosphates such as disodium phosphate (for example the dodecahydrate, heptahydrate, dihydrate and anhydrous forms) or sodium phosphate and mixtures thereof (for example McIlvaine""s buffer which is a mixture of citric acid and disodium phosphate).
In a particular aspect the pH of the pharmaceutical formulation of zolmitriptan is below 6.0, for example in the range 3.5 to 5.5, and in particular in the range 4.5 to 5.5. In a particular aspect the pH of the formulation is about 5.0.
In addition to the buffer, the zolmitriptan formulation may contain other ingredients typically found in intranasal formulations, such as antioxidants for example sodium metabisulphite, taste-masking agents such as menthol and sweetening agents for example dextrose, glycerol, saccharin and sorbitol.
In another aspect the present invention provides an aqueous solution of zolmitriptan in a buffer at a pH of less than 7.0 in particular at a pH below 6.0, for example in the range 3.5 to 5.5 and in particular in the range 4.5 to 5.5, for example at about 5.0. In particular the present invention provides an aqueous solution of zolmitriptan in a buffer of citric acid and phosphate at a pH of less than 7.0, in particular at a pH below 6.0, for example in the range 3.5 to 5.5 and in particular in the range 4.5 to 5.5, for example at about 5.0.
The pharmaceutical formulation of the present invention may be co-administered (simultaneously or sequentially) with one or more pharmaceutical agents of value in treating migraine or related disease conditions.
The pharmaceutical formulations of the invention will normally be administered to humans so that, for example a unit dose of about 0.5 mg to 15 mg (for example 0.5 mg, 1.0 mg, 2.5 mg, 5.0 mg and 10 mg) of zolmitriptan is delivered to the patient in need thereof. The concentration and volume of the formulation may vary as known in the intranasal art, typically a volume of 50 to 250 xcexcl is administered, for example 50 xcexcl or 100 xcexcl (in one spray or in two 50 xcexcl sprays-13 one for each nostril), The precise dose delivered depends on various factors known in the art including the weight, age and sex of the patient being treated and on the particular migraine disease condition being treated. Such a unit dose may be taken at any stage in the onset of, or during the course of, a migraine attack. Such a unit dose may be taken as needed, typically from 1 to 3 times a day.
The pharmaceutical formulations of this invention may be prepared by dissolving zolmitriptan in an acidic medium, for example aqueous citric acid, thereby forming the citrate salt of zolmitriptan, and taking the pH to the desired value by adding a suitable agent for example a phosphate. The resultant buffered solution is typically manufactured to ensure that it contains a low bioburden or to ensure that it is sterile. Typically the solution is sterilised for example by passing through a sterile filter (for example 0.2 xcexcm) or by autoclaving. Preferably, the solution is purged with nitrogen, and overlaid with nitrogen in the primary pack, to minimise the possibility of degradation. Alternatively, another inert gas, such as argon, could be used. Therefore in another aspect the present invention provides a sterile pharmaceutical formulation suitable for intranasal administration which comprises zolmitriptan and a pharmaceutically acceptable carrier wherein the pH of the formulation is less than 7.0.
The pharmaceutical formulations of the invention are typically filled into a suitable administration device capable of delivering a unit dose amount of zolmitriptan to the patient in need thereof. Such administration devices include those available commercially and the device disclosed in UK Registered Design 2071555. Therefore in a another aspect, the present invention provides an intranasal administration device containing zolmitriptan and a pharmaceutically acceptable carrier wherein the pH of the formulation is less than 7.0.
The filled intranasal administration device may be packaged to provide protection from light. Accordingly in yet a further aspect, the present invention provides an intranasal administration device containing zolmitriptan and a pharmaceutically acceptable carrier in light-protecting packaging, for example in foil pouches. In an alternative aspect the device itself is a dark colour to provide protection from light, for example, a dark blue colour.
Therefore in a further aspect the present invention provides a pharmaceutical formulation suitable for intranasal administration which comprises zolmitriptan and a pharmaceutically acceptable carrier wherein the pH of the formulation is less than 7.0 for use in a method of therapeutic treatment of the human or animal body.
In yet a further aspect the present invention provides a method of treating a disease condition wherein agonism of 5HT1-receptors is beneficial which comprises administering an effective amount of a pharmaceutical formulation suitable for intranasal administration which comprises zolmitriptan and a pharmaceutically acceptable carrier wherein the pH of the formulation is less than 7.0. The present invention also provides the use of zolmitriptan and a pharmaceutically acceptable carrier in the manufacture of a pharmaceutical formulation suitable for intranasal administration wherein the pH of the formulation is less than 7.0.
Zolmitriptan used in the formulations of the present invention may be prepared according to the disclosures of WO 91/18897 and WO 97/06162.